Characterization and modelling of biosorptive performance of living cells of Bacillus arsenicus MTCC 4380 for the removal of As(III) and As(V)

One of the main environmental concerns of today is the occurrence of arsenic in wastewater. Targeting a solution for this problem, several efforts have been made towards research and application of cost-effective and easily adaptable processes for removing arsenic. The potential of living cells of Bacillus arsenicus MTCC 4380 to biosorb both As(III) and As(V) was examined in batch experimentations targeting the treatment of wastewater with high concentrations. Optimum parameters for biosorption process were determined as a function of contact time and temperature. The equilibrium was achieved after about 90 min at 30 °C temperature. Non-linear regression analysis was done for determining the best-fit kinetic model based on three correlation coefficients and three error functions and also to predict the parameters involved in kinetic models. The results showed that both Brouers–Weron–Sototlongo models for both As(III) and As(V) were proficient to provide realistic explanation of biosorption kinetic. Applicability of mechanistic models in the current research showed that the rate controlling step in the biosorption of both As(III) and As(V) was film diffusion rather than intraparticle diffusion. The estimated thermodynamic parameters ΔG°, ΔH° and ΔS° exposed that biosorption of both As(III) and As(V) was exothermic, spontaneous and feasible under studied conditions. The activation energy (Ea) estimated from Arrhenius equation specified the nature of biosorption being ion exchange type. The results acquired are very favorable and encourage the use of living cells in environmental applications.